Authentication systems are used for security purposes to verify the authenticity of one or more parties during a transaction. In the past, transactions were of a more personal nature, in that authentication consisted of the vendor visually recognizing the purchaser, or identifying the purchaser's voice. As transactions become ever more impersonal, additional authentication can become increasingly necessary.
Authentication systems can be manual, such as when purchasing an item with a personal check. The purchaser can present additional identification, such as a driver's license, to verify the authenticity of the purchaser. Authenticating systems can also be electronic, such as when using an Automated Teller Machine (ATM). The ATM card can include account and customer information. To guard against unauthorized access, the user of the ATM must input a Personal Identification Number (PIN). The correct PIN serves to authenticate that the user is the customer authorized to use the ATM card.
Some existing authentication schemes generally rely on information that can be readily obtained, thus compromising the authentication. For example, a fraudulent license can be provided when purchasing items by check. The Internet provides many opportunities for obtaining personal identification information, as witnessed by the increasing threat of identity theft.